Pressure actuated switch



July 10, 196 G. e. GUTHRIE PRESSURE ACTUATED SWITCH Filed Feb. 25, 1960 INVENTOR GEORGE G. GUTHRIE BY imm United States Patent 3,043,929 PRESSURE ACTUATED SWITCH George G. Guthrie, 1164 N. Vancouver St., Tulsa, Okla. Filed Feb. 25, 1960, Ser. No. 10,921 3 Claims. (Cl. 200-83) a pressure sensitive switch in which a micrometer setting is provided for determining the pressure at which the switch is actuated and which further provides means for locking the sensing mechanism in the position determined by the micrometer setting.

It is still another object of the present invention to provide a pressure sensitive switch in which the pressure sensing and switch actuating mechanisms are mounted on a unitary structure so that the pressure setting may be determined and set into the mechanism after which the mechanism may be inserted as a unit into its housing.

It is yet another object of the present invention to provide a pressure sensitive switch having a pressure-responsive, axially moving switch actuator and a switch whose position relative to the end of the axially moving actuator is determined by a micrometer setting which setting may be maintained by means of a locking mechamsrn.

The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a vertical section in elevation of the as sembled switch of the present invention; and

FIGURE 2 is an exploded view in elevation of the switch of the present invention.

Referring now specifically to the figures of the accompanying drawing, there is provided a generally T- shaped main connecting housing 1 having an axially bored, downwardly depending leg 2 and a generally horizontal cross member 3 having an enlarged internal aperture 4. The exterior of the leg portion 2 is provided with threads 6 so that the member of the leg or stem 2 may be threaded into an apparatus, the internal pressure of which is communicated to a bore 5 in the leg 2. The internal bore 4 of the cross portion 3 is provided with internal threads 7 which are adapted to receive external threads 8 on the lower end of an internal housing 9. The main connecting housing 1 is provided with a hexagonal, outwardly extending flange 11 which is adapted to receive a hexagonal seat 12 of a main cover or housing 13.

A pressure sensitive diaphragm 14 is adapted to be seated on an internal horizontal ledge 16 which defines the lower surface of the enlarged internal bore 4 of the main connecting housing. The diaphragm 14 is disposed over the central 'bore 5 of the downwardly depending leg 2 of the main connecting housing 1 and the center portion is moved vertically in response to variations in pressure internally of the apparatus into which the stem 2 is threaded. A piston or actuator rod 17 has a head portion 18 located at its lower end which is in contact with the center of the diaphragm 14. A lower diaphragm seal 19 is disposed about the head portion 18 of the piston 17 and serves to prevent leakage around the diaphragm. A spring seat or washer 21 is adapted to be disposed about the piston 17 and to engage the upper surface of the head portion 18 thereof so as to transmit Vil 3,043,929 Patented July 10, 1962 the force of a spring 22 to the piston 17. The spring 22 is retained by a spring retainer nut 23 which is a generally hollow, cylindrical member having an end wall 24 and external threads 26 about its lower end. The end wall 24 is provided with a small central aperture 27 through which the piston 17 passes and the external threads 26 thereof are adapted to engage internal threads 28 of the inner housing member 9. The threads 28 terminate in an inwardly directed shoulder 29.

In assembly, the diaphragm 14 is placed against the shoulder 16, the piston 17 and has its head 18 positioned against the diaphragm. The seal 19 is slipped over the piston 17 and thereafter, the spring ring 21 is passed down over the piston 17 and brought into engagement with its head portion 18. The spring 22 is then passed over the stem of piston 17 and the member 9 is threaded into the main connecting housing 1 with the threads 8 of the former housing engaging the threads 7 of the main'connecting housing. The spring retainer nut is then threaded into the housing 9 and screwed down until its lower surface engages the inwardly extending shoulder 29 of the internal housing 9.

The internal housing 9 is provided with an upper set of internal threads 31 adapted to receive external threads 32 formed on the lower end of an adjustable switch housing 33. The adjustable switch housing 33 is generally hollow and has a pair of upwardly extending, rectangular walls 34 and 36 which are spaced from and parallel to each other. A microswitch 37 is adapted to be supported between the vertical walls 34 and 36 and retained therebetween by means of screws 38 which pass through appropriate apertures 39 in the wall 36 and apertures 41 in the body of the switch 37 and thread into apertures 42 in the wall 34. Thus, the switch 37 is suspended in a fixed position between the side walls 34 and 36. The threads 31 of the internal housing 9 and threads 32 of the adjustable switch housing 33 are micrometer threads which permit very fine and accurate adjustments to be made of the position of the housing 33 with regard to the housing 9. The position of the housing 9 with respect to the main housing 1 is fixed once the switch is assembled since the housing 9 is screwed into the main connecting housing 1 until their adjacent horizontal shoulders are brought into engagement. The length of the piston 17 remains substantially constant in any given working environment so long as the temperature is relatively constant and therefore by providing an accurate adjustment of the relative position of the housing 33 with respect to the housing 9 an accurate pressure sensing mechanism is provided.

The switch 37 is provided with an actuating mechanism 43 which depends downwardly from the under side of the switch as seen in FIGURE 1 and is adatped to be disposed immediately above the piston 17. Therefore, upon adjustment of the position of the housing 33 with respect to the internal housing 9, the point at which pressure transmitted to the diaphragm 14 through the passage 5 actuates the switch 37 may be accurately controlled. A pair of set screws 44 and 46 are employed to positively retain the setting of the housing 33 with respect to the housing 9. More specifically, the set screws 44 and 46 pass vertically through threaded apertures in the housings 33 and engage the upper surface of the housing 9. By tighting these screws so as to develop a force between the threads 32 and 31 of the members 33 and 9, any setting of the member 33 with respect to the member 9 may be retained for a considerable period of time.

It will he noted that the assembly thus far contains all of the pressure sensing elements required to actuate the switch 37 in response to a predetermined pressure and therefore, the entire mechanism may be calibrated as an assembled unit. Thereafter, outside cover 13 may be slipped down over the assembly until its hexagonal flange 12 is in engagement with the hexagonal flange 11 of the main connecting housing 1. A plurality of screws 47 may be employed to connect and secure the flanges to one another thereby enclosing the operating mechanism. The hollow cylindrical housing 13 is provided with a upper end wall 48 having a central aperture 49 formed therein. The switch 37 is provided with a plurality of terminals 51 which are to be connected by means of wires 52 to terminals 53 of a connector The connector 54 is adapted to be seated on the end wall 43 and its terminals 53 pass through the aperture 4? in the end wall. The leads 52 are secured between appropriate terminals 51 on the switch 37 and terminals 53 on the terminal connector 54. Actually, the leads 5?. are connected to the terminals 51 prior to assembling the hous ing 13 to the main connecting housing 1 and the leads are brought out through the aperture 49 soas to permit soldering to the terminals 53. Thereafter, in assembling, the wires are pushed back inside the housing and the connector 54 is secured to the upper surface of the housing by a flange or sealing ring 5-6 secured to the housing 13 by means of bolts 57.

It will he noted from the above description that the entire operating mechanism is a self-contained unit which may be readily adjusted prior to final assembly so as to facilitate assembly and calibration. Further, the pressure at which the switch 37 is actuated is adjusted by a micrometer setting resulting from the setting of micrometer threads 31 and 32. The setting is positively retained by set screws 44 and 46. The calibration of the spring 22 is positively retained so long as temperature conditions are not severe and since the housing 9 has a positive position with respect to the housing 1 and the spring retainer 23 has a positive position determined by the flange 29 with respect to the housing 9, the calibration of the unit is fixed. Therefore, the only variable in the system is the position of the adjustable switch housing 33 with respect to the housing 9 and this setting is controlled by means of a micrometer arrangement.

While I have described and illustrated one specific embodiment of my invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined by the appended claims.

What I claim is:

l. A pressure actuated switch comprising a main connecting housing having a small central bore and an enlarged central bore, a pressure sensitive diaphragm disposed in said enlarged bore and covering one end of said small bore, a hollow internal housing threaded into said enlarged bore of said main connecting housing, said housings having abutting surfaces when assembled, a

switch, a switch housing having a set of external micrometer threads at one end thereof, said switch being mounted centrally internally near substantially the opposite end of said switch housing, said internal housing having a set of micrometer threads adapted to receive said micrometer threads of said switch housing, said switch having a switch actuator, a rod extending between said diaphragm and said actuator, means for exerting a predetermined force on said rod opposing the force of the pressure applied to said small central bore of said main connecting housing, said means comprising a head portion on one end of said rod with said head portion engaging said diaphragm, seat means positioned on said rod in circumjacent relation thereto and in engagement with said head portion, a spring positioned on said rod in circumjacent relation thereto and engageable at one end with said seat means, means positioned on said rod in circumjacent relation to said spring and engaging the opposite end of said spring for developing a predetermined compressional force in said spring, said last-mentioned means comprising a hollow cylindrical member having an end wall with a central aperture, a set of external threads adjacent an end of said member remote from said end wall, said internal housing having internal threads in threaded engagement with the external threads of said member, said spring being disposed internally of said member with the end wall thereof in engagement with the opposite end of said spring, said rod Passing through the aperture in said end wall and said member and said internal housing having abutting transverse shoulders.

2. The combination according to claim 1 further comprising at least two threaded apertures extending longitudinally through said switch housing and opening adjacent an end wall of said internal housing, at least two bolts in threaded engagement in said threaded apertures and adapted to be brought into contact in said end wall.

3. The combination according to claim 1 further comprising a hollow externalhousing releasably secured to said main connector housing and enclosing said internal housing and said switch, said external housing having an apertured end wall, a connector secured to said end wall, said connector having terminals extending through said aperture in said end wall of said external housing, said switch having electric terminals, and leads interconnecting said switch terminals and said connector terminals.

References Cited in the file of this patent UNITED STATES PATENTS 1,938,327 Green Dec. 5, 1933 2,722,580 Hasselhorn et al. Nov. 1, 1955 2,880,909 Clymer et al. Apr. 7, 1959 

